Logic Masters Deutschland e.V.

By shye, Ben, xoned, abed hawila, Botaku, ahaupt, Hackiisan, Qinlux, Ethz, Philip Newman, Zack Szekely, Strosahl, Reverend, Gliperal, and yours truly.

This puzzle is based on a collaboration puzzle by 15 authors. At some point it was my turn. I added a killer cage somewhere, attempting to create some interesting logic, but it turned out that this cage imploded the puzzle to only 2 solutions, without creating much of a solve path. Completely astonished by this, I had to figure out why. I can't say that I found a satisfactory answer, but this research did lead to a puzzle that I think is interesting enough to publish. All this does mean that the list of rules is longer than usual:

• Normal sudoku rules apply.
• Quadruple: the white circle with '1248' indicates that each of these digits must appear in one of the cells adjacent to the circle.
• Clones: the two 2x2 grey areas in boxes 4 and 8 are clones. They contain identical digits in identical positions within the 2x2 grey area. The top left (r1c1) and bottom right squares (r9c9) are clones as well, and must contain the same digit.
• Killer cages: an area surrounded by a dashed line is a 'cage'. Digits in a cage cannot repeat and sum to the number in the upper left corner.
• Thermometer: the grey path indicates a thermometer. Digits in thermometers must increase from the bulb.
• Kropki pairs: a black dot between two cells means that one of the digits in the cells is exactly double the other. Not all possible black dots are given.
• Odd/even: Cells with an opaque grey circle must be odd. Cells with an opaque grey square must be even.

You can play this puzzle online using f-puzzles: https://f-puzzles.com/?id=ygtxxhnn.

Hope you will enjoy!

The break-in is the same as in the original puzzle. Because of this, I thought it appropriate to credit all original authors, regardless of whether or not their clue survived.

See https://f-puzzles.com/?id=yxk93l2d for the original puzzle.